1. Field of the Invention
The invention relates to the field of spread spectrum communication.
2. Prior Art
Digital communications over power lines as well as other media using a spread spectrum signal which relies on correlation for the detection of the digital signals is well known. For example, see U.S. Pat. No. 4,979,183. Other examples of such communications can be found in U.S. Pat. Nos. 5,289,498; 5,263,050; 5,090,024; 5,278,862 and 5,359,625.
The spread spectrum signal can in some cases be distorted, particularly on power lines. For example, a power supply in a television can sufficiently distort the signal to cause misdetection. In co-pending application Ser. No. 08/534,574, filed Sep. 27, 1995, entitled xe2x80x9cSplit Band Processing for Spread Spectrum Communicationsxe2x80x9d (assigned to the Assignee of the present invention) an apparatus and method are described for dealing with the distortion by, in general terms, dividing or splitting the broad band, spread spectrum signal into sub-bands and separately processing the sub-bands before recombinating the sub-bands.
The present invention provides another method and apparatus where the reference pattern used for detecting data is altered either by using different patterns or by using an adaptive pattern.
The invention describes several different patterns for use in correlation with a received signal in a spread spectrum system. In one embodiment, a standard reference pattern is used with an alternate pattern selected to provide higher correlation values in the presence of certain channel distortion. In another embodiment, samples from the received signal are used to provide an adaptive correlation reference signal. Other embodiments are described in the detailed description of the invention.